Videocolor

Nicola D Cagna

Carlo L Fonda

The present invention provides an improved method of forming a shadow mask for a color picture tube from a flat apertured mask. The mask has an central apertured portion, a solid border portion and a skirt portion. The improved method comprises several steps. First, a flat apertured mask is placed beneath an upper punch. Next, the periphery of the mask at the skirt portion is clamped. The punch then is pressed against the mask to contour the mask in its central apertured and solid border portions. Thereafter, the periphery of the mask at the skirt portion is unclamped, and the solid border portion of the mask is pressed between a bead die and the punch to form a peripheral bead in the solid border portion of the mask. Finally, the skirt portion is swept back to substantially parallel a central longitudinal axis of the formed mask, while the border portion is held between the bead die and the punch.

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Rome, Italy

Nicola D Cagna